It looks like a handyman's repair diagnosis for a tube-powered TV. The comments in the "newest" ink from 1969 indicate testing/replacing all of the tubes except two ("band still there" may indicate a horizontal electrical disruption in the picture) then replaced the last two with two used (but still testing "barely green") 6GU7s, which resulted in "band gone."

I enjoy your blog; I used to be a carpenter and working in older homes had a similar fascination with the discarded/forgotten things I'd find in closets, attics, or even walls.

It looks like a handyman's repair diagnosis for a tube-powered TV. The comments in the "newest" ink from 1969 indicate testing/replacing all of the tubes except two ("band still there" may indicate a horizontal electrical disruption in the picture) then replaced the last two with two used (but still testing "barely green") 6GU7s, which resulted in "band gone."

I enjoy your blog; I used to be a carpenter and working in older homes had a similar fascination with the discarded/forgotten things I'd find in closets, attics, or even walls.

A color TV tube schematic. The guy's testing the tubes to see which one (or ones) is bum. I have memories of my mother (in the 60's) going down to Sprouse Reitz 5&10, which had a tube tester, to test the tubes when our TV wasn't working. If she could fix it and not need to call in an expensive repairman ...

One of the tubes mentioned: "The 6GU7 is a medium-mu twin triode of the 9-pin miniature type intended for use in the matrixing circuits of color television receivers." [ref: http://www.shinjo.info/frank/sheets/135/6/6GU7.pdf ]